Field of the Invention
The present disclosure relates to a device and a method for controlling an air suspension system. More particularly, it relates to a device and a method for controlling an air suspension system, which improve durability of a bellows of an air spring, which supports a load of a vehicle when the vehicle is parked, by reducing a fatigue degree of the bellows.
Description of Related Art
A suspension system for a vehicle is an apparatus that blocks vibration or impact, which is transmitted from a road surface while the vehicle travels, from being transmitted directly to a vehicle body, thereby preventing the vehicle body and freight from being damaged, preventing passengers from being injured, and improving ride quality of the vehicle. As main components of the suspension system, there are a chassis spring which attenuates impact transmitted from the road surface, a shock absorber which controls vibration of the chassis spring, a stabilizer bar which prevents rolling motion of the vehicle, and the like.
Among the above components, the shock absorber is mounted between the vehicle body and a wheel in order to absorb vibration, which is caused by impact transmitted to the chassis spring while the vehicle travels, and quickly attenuate the vibration, thereby improving ride quality.
A suspension system, which includes an air spring together with the shock absorber, is called an air suspension system.
Meanwhile, the air spring supports the vehicle body by using elastic force of compressed air, and absorbs and mitigates vibration and impact transmitted from the road surface. Because the air spring is configured to change air pressure in a bellows by using a separate compressor, the air spring may adjust a height of the vehicle body by adjusting air pressure in the bellows, thereby maintaining a predetermined height of the vehicle body regardless of the number of occupants.
The bellows, which is one of the components of the air spring, is an extendable and contractible air chamber that accommodates compressed air, and always receives air pressure at a predetermined level. Therefore, the bellows is manufactured by arranging cord yarns and rubber at predetermined intervals so as to have a structure that is advantageous to tensile force in order to withstand very high air pressure.
However, the bellows having the above structure also has problems in that the rubber portions burst which cause pinholes while the cord yarn and the rubber are separated from each other due to a load transmitted in a field, an air leak occurs due to the pinholes, and as a result, the air spring cannot support the vehicle body, whereby the vehicle collapses.
In order to solve the above problems, a number of man hours (M/H) are required to find out influential factors that affect a lifespan of the bellows.
Because the method of using the cord yarn and rubber to manufacture the bellows has advantages and disadvantages in terms of behavior properties of the air spring, a bellows with an axial ply structure which has wrinkled portions that extend in an axial direction, a bellows with a cross ply structure which has wrinkled portions that extend in a diagonal direction and intersect each other, and the like are applied. However, even though any one of the bellows with the above structures is selected and applied to the air spring, it is difficult to basically solve the problems in respect to the occurrence of the pinholes in the bellows because the pinholes are formed in the field as time passed in a state in which the air spring is mounted in the vehicle.
In the field, the pinholes formed in the bellows of the air spring are caused by physical properties of the rubber material that constitutes the bellows. The air spring always accommodates high-pressure air in the bellows in order to support a load of the vehicle, and accordingly, age-hardening gradually occurs at folded portions of the bellows, which are exposed to high air pressure, such that the bellows is permanently deformed, and an elongation percentage of the bellows deteriorates. Therefore, the pinholes are formed by fatigue caused by repetitive extension and contraction in up and down directions at the folded portions of the bellows which are weakened.
Since the bellows supports the load of the vehicle not only when the vehicle travels but also when the vehicle is stopped over a long period of time such as when the vehicle is parked, fatigue is accumulated on the bellows.
Meanwhile, according to a result of statistically analyzing actual driving time of the vehicle, the driving time of the vehicle is less than half a period of time for which a user owns the vehicle, and therefore, it may be considered that the vehicle is parked for most of the period of time for which the user owns the vehicle.
In general, the suspension system of the vehicle or components of the vehicle body are not damaged by fatigue in a mode in which there is no repetitive load such as when the vehicle is parked. However, a component such as the bellows of the air spring is damaged by fatigue even when the vehicle is left unattended over a long period of time such as when the vehicle is parked because the component needs to support a high load of the vehicle.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.